Production of coloring matters



Patented Apr. 10, 1923.

UNITED STATES PATENT OFFICE.

WILLIAM JACKSON POPE, OF HOLMESDALE, CAMBRIDGE, ENGLAND, ASSIGNOR OF ONE-HALF TO SCOTTISH DYES LIMITED, OF CARLISLE. CUMBERLAND, ENGLAND.

PRODUCTION OF COLORING MATTERS.

No Drawing.

To all whom it may concern:

Be it known that I, \VILLIAM JACKSON Porn,a subject of the King of Great Britain and Ireland, and residing at Holmesdale, Brooklands Avenue, Cambridge, in the county of Cambridge, England, have invented certain new and useful Improvements Relating to the Production of Coloring Matters, of which the following is a specification.

This invention relates to improvements in the manufacture of N dihydro-lz2:1'22- anthraquinoneazine and its derivatives.

The blue coloring matter, N-dihydrod 2: 1' :"-anthraquinoneazine is usually prepared by the action of fused caustic potash on 2-aminoanthraquinone with or without the addition of an oxidizing agent followed by atmospheric oxidation of a solution of the melt.

The present invention has for its object to provide a process giving improved yields of N-dihydro-1r2:1:2'-anlhraquinoneazine.

The object of my invention also includes a process for the manufacture of the derivatives of N-dihydro-lzQ:1:2-anthraquinoneazine.

The invention consists in modifying the process referred to above either for the production of Ndihydro-l:2: 1'1 'anthraquinoneazine or of its derivatives, by causing the action of fused caustic potash on Q-aminoanthraquinone or its derivatives respectively to take place in the presence of a salt of an organic acid which is miscible in a fused state with the alkali.

The invention also consists in the introduction into the melt at any appropriate stage of an oxidizing agent for the purpose of still further improving the yield and purity of the N-dihydro-l:2:1:2-anthraquinoneazine or of its derivatives The invention also consists in fusing a body containing the group with caustic alkali in the presence of potassium formate and obtaining a coloring matter by subsequent oxidation.

In this specification and claims Where I have referred to N-dihydr0-1:2:1:2'-an- Serial No. 410,913.

thraquinoneazine without specifically mentionin its derivatives the term is to be read as incfuding such derivatives.

Further, where I have referred to the this includes that group with or without one or more hydrogen atoms substituted in the anthraquinone nucleus.

In carrying the invention into effect in one form by way of example, I melt together potassium formate and Q-aminoanthraiquinone and subsequently add caustic potash to the molten mass.

I have found that on thus bringing 2- aminoanthraquinone into contact with fused caustic potash at a suitable temperature in the presence ofan appropriate molten salt, N-dihydro-l :2 :1 :2-anthraquinoneazine is produced in better yield and in a higher state of purity than in the absence of the above mentioned salt. N-dihydro1:2:1:2'- anthraquinoneazine is not produced in the melt but is formed and precipitated by subsequent air oxidation. I have also found thatv instead of 2-aminoanthraquinone its simple derivatives may be employed (in which case the derivatives of N-dihydro- 1:2: 1' :2-anthraquinoneazine are formed). A number of salts of organic acids are known which form homogeneous liquids when melted together with caustic alkali and such mixtures remain liquid. at temperatures below those at which the production of N-dihydro-l:2:1' :2-anthraquinoneaZine or its derivatives from Q-aminoanthraquinone or its derivatives is brought about by contact with fused caustic potash. Thus, as a further example, potassium acetate may be employed instead of the potassium formate referred to above.

Again, mixtures of two or more suitable salts may be employed, for example, mixtures of potassium formate and potassium acetate, and the action may be very advantageously modified by the presence of water, or other inert solid or liquid diluent for the purpose of lowering the fusing point of the mass.

According to a further modification the process may be carried out by adding 2- aminodifihifaljiiihone or one of derivatives to a fiisefd mixture of potassium fol-matte or acetate with caustic potash.

:Suitable oxidizing agents may be introduceclzat any appropriate stage into the melt for the purpose of still further improving the yield and value of thep'roduced Ndihydro-lz2:1:2'-anthraquinoneazine or its derivatives.

Having now described my invention, YYlL ii Ismail as new and desire to se'cui b Lttrs Patent is: p I d g. A process "fo f the mm iufactgf'fifi N- 1 ydro-l :2 :1 z2-anthraquinoheaztile which consists in acting on Q-aminoanthruquinbiie by fused caustic po'tashiinthe presence of a salt of an orgahic acid vvfhich is miscible in a fused state withithe alkali and subsequently isolatingthedyestuff by oxidation.

2. A rocess .asjclaimed in claim 1, in if fdi-mat is employed as the 8f 8 hicacid.

3. A process as claimed in claim 1, in My ffmilt tiiie's of salts Hf organic acids h d" iificess is claimed in claim 1, in ti'hlc'h {in ihert diluent is employed in conjunction with the aforesaid bodies.

[5. .A process as claimed in claim 1. in onidizili agent is introduced into the melt fot 'thegiii pose of impiot'ing the yield and purity of the roduced N-dihydrolz2z'lff 2 ointhj'a 11in awe; V

6. A process a "cla get i'h claim '3, in which mixtures of potassium formate and potassiumcflqetflfism m toyed.

7. A prggess asclaime in claim 1, in which potassium formate is employed as the saltofitiiewrganie acid and an inert diluent is used in conjunction therewith. ""SI'TK process as claimed in claim 1, in

with caustic alkali in theprese nc oflpdtas sium formate and obtaining a coloring mittter, by subsequent oxidation.

In testimony whereof I have signed thy name to this specification.

WILLIAM JACKSON POPE. 

